First version of join in movie room

* User can choose a movie and join in it

Functions for the folowing commits:
* Update userlist when user join in a movie room
* Leave movie room and back to the main room
* Send messages in movie room
Fix bug of header encoding

* The previous commits could not pass the tests was because of the
  mistake header shifting, witch means the tests' explanation and the
  protocol's explanation of the specification were not the same!
Merge branch 'master' into changeroom

Conflicts:
	c2w/protocol/util.py
Fix some bugs for passing tests

* send movie list
* duplicate user login
Finish jump between rooms
Finish userList update for all cases & Fix bugs
Add sending and forwarding message in movie room
Fix bug of length when sending user list